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Vacuum cleaner clogged condition indicator

  • US 3,936,904 A
  • Filed: 06/03/1974
  • Issued: 02/10/1976
  • Est. Priority Date: 06/03/1974
  • Status: Expired due to Term
First Claim
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1. In a vacuum cleaner having an air suction means including drive means, collecting means for removing entrained material from air flowed therethrough by said suction means, and means for conducting said air in heat transfer association with the drive means for cooling the drive means, means for indicating an undesirable clogging of the collecting means comprising:

  • electrically operable indicator means carried by said vacuum cleaner;

    thermally responsive means for operating said indicating means when the thermally responsive means is heated to above a preselected temperature including a positive temperature coefficient resistor electrically connected to said indicator means for varying the effective voltage applied thereto;

    heater means having a preselected heating capacity for heating said thermally responsive means to above said preselected temperature; and

    thermally conductive means mounting said heater means and thermally responsive means in heat transfer association, at least one of said heater means and said thermally responsive means being in heat transfer association with the sucked air subsequent to its conduction in heat transfer association with said drive means for maintaining the thermally responsive means at a temperature below said preselected temperature when the collecting means is substantially unclogged whereby said indicating means is precluded from operating and thereby indicate the substantially unclogged condition of said collecting means, and permitting the heater means to heat said thermally responsive means to above said preselected temperature when the collecting means is substantially clogged whereby said indicating means is caused to operate and thereby indicate the substantially clogged condition of said collecting means.

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